Senior moment.............!

[SirKit Breaker]

Please help the aged. I had one of my students doing ring final circuit continuity testing, and he asked me why we got a quarter of the r1+r2 value at any given outlet. for the life of me i cant remember the calculation.:confused5:

cheers...........Howard

 

[Sparky Ninja]

r1+r2/4 is the formula Howard.

We get this value as the figure of 8 connection creates the scenario where we half the length, and double the csa of the conductor.

Ergo the resistance is actually halved, twice. i.e. quartered.




Just attached an image that may help, it's not to 17th though.

 

[telectrix]

and the readings are the same at each outlet because the ends are cross connected.

 

[Knobhead]

We all have those moments, wouldn’t human if we didn’t. One of the reasons why I liked having an apprentice with me on faults.
They will ask you a question and want an explanation for something you’ve gone in to “auto pilot” on. I’m franticly trying to get the brains out of the back pocket at that point.

 

[oldtimer]

I had a moment last week when I stepped in the bathtub to test the Zs of a shower circuit so I had my MFT 1553 primed but when I put it on the connections there was no supply so I leaned over and pulled the cord only to discover the shower goes through a flush cycle so i got a shot of water all over me. Thank god there was no apprentice their.

Mind you did well to protect my MFT